Fishing tool



Oct.7 14 1952 K, C, HAWKINS 2,613,980

FISHING TOOL Filed March 13, 1950 HUE' BNE 1?,.85 E HL E R WORRE L yHERZ/G 8 CALDWELL,

A TTORNEYS.

Patented Oct. 14, 1952 UNHTED STATES PATENT FFICE 25,613,980

y msnm@ rrootJ Kenneth e. Hawkins, Arcadia, cani. Application March 13,1950, Serial No. M926@ 3 Claims.

application relates to shi'ng tools particularly adapted to retrievingmagnetiaable obiects from well casings and to tools which are foundparticularly advantageous in deep well casings of the type usedextensively in sinking oil wells. 5

In oil well '.irilling where it is the practice to sinh oil wells intothe earth accompanied by steel oasings to distancesA of thousands offeet drilling operations become particularly expensive. Al.- thoughtools have been contrived which may eventually bring objects in the wellto the suriaoe, excessive time consumed in suchoperations interferes'with or interrupts the drilling before vthe desired depth is reachedand causes objectionable and sometimes prohibitive loss of timefrequently jeopardizing the economic success of the operation. Thereforewhen objects such as wrenches, drill bits, sections of pipe and the likeinadvertently fall into the casing the time and snort required toretrieve them is a substantial factor in drilling operations. 'Moreoventhe deeper the well, the more time is lost espeoially when objects,partly retrieved, are lost or dropped a second time making necessary newefforts to lift them.

Heretofore a great variety of fishing tools have been devised utilizingone mechanical expedient or another for grappling objects which havefallen into the well with a sufficiently tight grip so that they may behauled upwardly out of the casing throughout distances of some thousandsof feet. Naturally the greater the depth of the well the longer is thetime needed to lower and raise the shing tool.` Unless the grip of thetool on the object to be retrieved is sufficiently' secure, the hold onthe object may be dislodged one cr many times before the object is nallypulled out of the casing at the surface. The cost of the shing operationis therefore increased a considerable extent whenever the object is notsuccessfully retrieved during the rst fishing operation. Y

inasmuch as almost all objects which are likely to fall into a drilledwell are of a ferrous and therefore magnetic nature, the use of a magnetfor retrieving the objects has suggested itself in the past.v Thecharacter of a Well is, however, such that using a magnet has heretoforepresented such difficulties that successful utilization of magnets forthis purpose has been defeated. The fact that the well casing is of amagnetic material short circuits the magnetic field, thereby reducingits strength to an unworkable quantity when the magnet and sometimes theobject itself strikes against the interior of the casing.

When the object is of irregular shape the 'grip of the magnet may bedislodged by reason of the object bumping against the well casing on theway up even though the strength of the magnet lis not materiallyreduced. lSome objects which need to be retrieved are so heavy that thestrength of the magnet cannot be depended upon to continue to attractthe object with suiiicient force throughout the entire lift from thebottom of the well to the surface.

It is therefore among the objects of the invention to provide a new andimproved magnetic. shing tool for well casings kwhich is adapted toretrieve metallic objects of any and all sizes which are ordinarilydropped into the well.

Another object of the invention is to provide a new and improvedmagnetic iishing tool which utilizes an auxiliary retainer or grapplingdevice to provide an independent grasp upon the object to be retrievedwhilel it is being lifted to the surface of the well. v

Still another object of the invention is to provide a new and improvedmetallic fishing tool which is so constructed that the magnet isshielded from contact with the casing so as to maintain sufficienteffectiveness in the force of the magnet throughout the entire lift fromthe bottom of`the well to the surface.

Still another object of the invention is to provide a new and improvedmagnetic iishing tool for wells by which an auxiliary retainer orgrappling device can he released when the object to be retrieved isdrawn to the magnet so that the retainer forms either a support uponwhich the object may be rested while drawn to the surface or which, forobjects of considerable length, may be moved so as to grip the exteriorof the object in a way such that no matter how great the pull may beupon the object the grip will be held until the object is lifted clearof the well.

Still further among the objects of the invention is to provide a new andimproved magnetic nshing tool for wells wherein a magnet is movablyretained in a casing in a manner such that it can bel 'extended to aposition most advantageous for initially engaging an object to beretrieved and thereafter withdrawn tegether with the object toa'position in the casing wherein the object if need be may be grasped bysome auX- iliary mechanism, thereby adding to the grip upon the objectwhile the fishing tool is being withdrawn together with the object fromthe well.

VWith these and other objects in View, the invention consists in theconstruction, arrangement and combination of the various parts of thedevice whereby the objects contemplated are attained, as hereinafter setforth, pointed out in the appended claims and illustrated in theaccompanying drawings.

In the drawings:

Figure 1 is a longitudinal sectional View of the magnetic fishing toolwith the parts in initial position shown being lowered into a wellcasing.

Figure 2 is a longitudinal sectional View of the fishing tool showingits operation in grasping an object to be retrieved which has a lengthgreater than the length which could be accommodated within the fishingtool.

Figure 3 is a longitudinal sectional view of the fishing tool shown inengagement with a relatively small object for lifting the object from awell.

Figure 4 is a cross-sectional view taken on the line 4--4 of Figure 1.

Figure 5 is a fragmentary longitudinal sectional view showing one formof grappling means in an initially withdrawn position as for loweringinto the well.

Figure 6 is a longitudinal sectional View of a modiiied form of thedevice showing a permanent magnet.

Figure 7 is a cross-sectional view taken on the line 'I-1 of Figure 6.

When using magnetic force to recover, retrieve and withdraw amagnetizable object from a deep well special precautions need be takento assure a suflicient grip upon the device no matter what its shapewhile it is being attracted te the area within which a proper grip maybe secured upon it and also during the entire lift of the device fromthe bottom of the well to the surface. In the magnetic fishing tool ofthe present invention the tool includes a container for the magnet whichopens downwardly in such a manner that when the objects to be retrievedare within the iield of attraction of the magnet they may be drawn to aposition with respect to the iishing tool so that a iirm grasp upon theobjects may be l.

assured at all times regardless of the size or shape of the object orthe character of the interior of the well casing in which the iishingtool is used.

As shown in the drawings there is depicted a section of steel wellcasing I which may be assumed to be at any depth which might ordinarilybe reached by conventional well drilling methods. A magnetic fishingtool indicated generally by the reference character I I is shown beinglowered into the casing I0 by means of a cable I2 secured to the tool bya cable connection I3.

The iishing tool comprises in the example chosen a cylindrical containerI4 of somewhat elongated character which has its upper end closed by acover I and which has a lower open end I6. The container shouldpreferably be of a non-magnetic material such as copper or aluminum soas to form an eiiective shield to prevent anything within the containerhaving a magnetic contact with the steel of the casing I0.

Within the casing is a piston I1 having a sliding packing I8 so that thepiston forms a closed chamber I9 within the container. A tting 20mounted in a cover I5 provides access to the chamber I9 through aiiexible hose line 2| which connects tc a shut-off valve 22 locatedabove and outside of the casing ID. By this means the chamber I9 may beiilled with a suitable iiuid under pressure if desired and by means ofwhich the contents of the chamber may be exhausted.

Mounted upon and below the piston I1 is a coil 23 of an electro-magnetsupplied by one wire 24 to one terminal 25 of the electro-magnet. Theother terminal may be grounded if desired through the cable I2. The wire24 may be helical or in any event extendible by some conventional meansand permanently secured to a binding post 26. From the binding post awire 21 may extend upwardly through the casing to a suitable source ofelectric power.

To complete the electro-magnet there is shown a stationary core 28 ofmagnetizable material, a cylindrical portion 29 of which forms a centerfor the coil 23 and a lower portion 3U of which forms a flat face forthe magnet. The core is shown threadedly engaged at 3l with the pistonso that the piston and the magnet act as a single unit.

For proper protection of the winding of the magnet there may be provideda non-magnetic wrapping 32 entirely surrounding the coil and the outercircumference of the portion of the core extending below the coil. Itwill be appreciated that fishing tools of this kind when extended deepinto wells are apt on occasions to be entirely submerged in mud andwater so that proper protection for the magnet is advisable. There must,however, be a suflicient clearance between the magnet and the inner wallof the chamber I9 so that the magnet and piston unit can raise and lowerwith perfect ease.

At the lower end of the container I4 there may be provided a shoulder 35upon which a complementaiy shoulder 36 on the magnetic core is adaptedto rest, thereby permitting a lower face 31 of the magnetic core toextend outwardly substantially iiush with the outside open end of thecontainer I 4.

In Figure 1 the electro-magnet is shown in its lowermost or extendedposition which is the position it would have While being lowered intothe well.

Figures 2 and 3 show the electro-magnet and piston unit in withdrawnposition removed from the open end of the container. This is theposition the electro-magnet piston unit will assume after the object hasbeen attracted to it and the electro-magnet withdrawn to the position itwill occupy while the fishing tool is lifted from the well.

At the lower end of the container there is provided a retaining meanswhich in the selected embodiment is shown as comprising oppositelydisposed arms 40 and 4I, 42 and 43. As shown in greater detail in Figure5 with respect to the arm 40 the container is provided with a recess 44adapted to receive the arm in a position sufiiciently withdrawn so thatthe electro-magnet piston unit is free to slide downwardly to lowermostposition. The arm is shown pivoted by means of a pin 45 to the lower endof the container and the stored energy of a spring 46 located behind thearm may be utilized to force the arm outwardly after the electro-magnetpiston unit has been lifted to a withdrawn position in the container I0.The arm may also be provided with a serrated or roughened section 4ladapted for use on special occasions in grasping the object which is tobe removed.

In operation fluid is pumped into the chamber I9 through the shut-offvalve 22 and hose line 2| so as to force the piston to lowermostposition. This is the position shown in Fig. 1. With the piston in thisposition the shut off valve is closed and the container loweredby meansof the cable I2 into the well casing. The core of the electro-magnetwill be at its outermost position substantially ush with the lower endof the casing during this operation.

When the fishing tool reaches the bot-tom of the well the magnetizableobject to be retrieved will be drawn to and attach itself by magneticforce to the exposed core of the electromagnet'. During this phase ofthe operation the electromagnet may be supplied withV current throughthe wire 24.

After theY attraction has been accomplished the piston together with theelectro-magnet is Withdrawn into the container to a position removedfrom the lower open end. These are'the positions shown in Figures 2v and3. This is accomplished by opening the shut-off valve 22 permitting theuid in the chamber i9 to bev discharged. The shut-off valve 22 is thenclosed again and the tool is lifted to the surface. As the piston israised, the wire 2li coils upon it self to the position shown in eitherFigure 2 or 3.

Movement of the electro-magnet together with the piston as thus -shownserves, in Figure to draw a section of pipe 48 upwardly and into thelower end of the container. Where as in this example the section of pipeis too longY to be entirely withdrawn into the container, the section ofpipe is grasped by the arms @il and 4I, 42 and 43. The grasp of the armsbecomes effective as the electro-magnet is lifted upwardly clear of thearms in the positions illustrated in Figure 5. After the electro-magnethas cleared, springs 4t will force the arms inwardly so that oppositearms are urged toward each other and into contact with the exteriorsurface of the object which in this case is the section of pipe 48. Uponengagement the serrated portions of the arms grip the exterior surfaceof the section of pipe and the weight of the pipe will cause the sectionof pipe to jam between opposite arms and thus provide a satisfactorygrip for the arms upon the section of pipe. The section of pipe thussecured is withdrawn to the surface by lifting upon the cable I2. Thusengaged it will not matter that the section of pipe touches the interiorof the steel casing since because of the auxiliary grip of the armsthere will be no short circuiting of the magnetic field such that itwill cause the section of pipe to be released. in fact the electric coilmay be deenergized once the section of pipe has been grasped andmechanical means depended upon solely for holding the section of pipewhile it is being lifted to the surface.

In the example illustrated in Figure 3 the object to be retrieved may bean object such as a large nut 50 still small enough to enter completelywithin the lower end of the container it. In this example after the nuthas attached itn self to the core of the electro-magnet and has beendrawn inwardly into the casing, es the electro-magnet and piston rise tothe withdrawn position, the arms MJ and si, 52 and 23 will drop forminga temporary false bottom for the con tainer. The width of the arms issomewhat arbitrary and may be proportioned as desired so that the armswhen lowered to the position shown in Figure 3 may cover substantiallyall or only a part of the open end. of the container lil. Theelectro-magnet will--of course remain energized until the nut is liftedclear of the arms. In their initial position as illustrated in Figure 5thesprings- 4f! willpush thel arms inwardly to a point from which theywill then drop by gravity to theY positionsshown in Figure 3. In thelowermost position there illustrated thel arms may be retained upon theshoulder Sii which initially served to bottom the electro-mae net.- Oncethe arms are dropped to the position shown in Figure 3 theelectro-magnet may be dee-energized and the object will be securely heidby the arms until it is lifted to the surface. l In the modified formofthe device shown in Figures S--and -7 there is illustrated a permanentmagnet 6l),l here shown as a double-pole magnet, having. two north poleslfill and 62 and two south poles 63 and Sil. Where a grip of lesserstrength is satisfactory a single-pole magn net may suffice. In theparticular example chosen for illustration the north and south polepieces are retained'against a magnetic disk 65 forming a piston by meansof a bolt 6E and a washer Eil. The disk 55 may be provided witharpacking ring 68, thereby serving as a piston adaptedY for-reciprocation sliding along the in ner wall 69 of the casing I4.Movement of the piston 55 is accomplished by the same fluid agency asdescribed in connection with Figure l.

In using a permanent magnet thel object to be retrieved will at alltimes be drawn toward the permanently magnetized poles. Although themagnet will at all times be shielded from contact with `the interior ofthe casing it by the interposition of the non-metallic jacket orcontainer lll, it is conceivable that the object to be retrieved mightbe so long that it protrudes outwardly below the container and also thatit might be of such character that it could not be iirmly gripped by thearms fill and il, i2 and d3. Under these circumstances the forces of themagnet entirely would have to be relied upon to hold the object inattracted position to the fishing toolv until the tool could be liftedclear of the well casing. Because the object to be retrieved is of amagnetizable character is therefore becomes particularly important thatthe magnet be shielded or guarded from direct contact with the wall ofthe casing which otherwise would tend to short circuit the magneticfield and diminish the magnetic force to a point where it would belikely to lose its grip upon the object being retrieved. Clearly too inthe last exame ple for objects small enough to be entirely withn drawninto the casing by action of the perinanent magnet, both the magnet andthe objects are positively shielded from contact with the walls of thecasing so that even if the operationA of arms 4i), el, 42 and 43 weredefective or jammed the magnetic force would continue undiminished byany short circuit to the end that the object` could be .liftedthroughout the full distance from the bottom of the well withoutbecoming dislodged.

0n some occasions Where the object to be re-1 trieved might not be ofany substantially great weight the magnet need not be extended to itslowermost position but lowered in withdrawn po-l sition in whichposition itcould be sunk to a point where the object would be within thefield of the magnet and the object thereby drawn into the open end ofthe container into contact with the magnet and even past the armswithout it being necessary to manipulate the magnet within thecontainer.

Once the fishing tool accompanied by the retrieved object has beenlifted clear of the well the arms can be pressed back sufficient torelease the object from the tool. Releasing of ythe object may befacilitated by laying the fishing tool on its side or on some occasionsturning it upside down so as to make easier the operation of releasingthe arms, In `the case of small objects held by the permanent magnetrelease may be more readily accomplished by forcing the iiuid into thechamber I9, thereby shifting the magnet to extended position in whichposition the retained object can be more readily dislodged.

Accordingly there has been provided a mechanism making the use ofmagnets in retrieving ob- Ijects from deep wells especially advantageousand successful which is clearly adapted to operate with great assuranceregardless of -the size or shape of any magnetizable object which couldfall into a well. It will be appreciated of course that in view of thefact that the diameters of well casings vary to some extent, fishingtools would be made small or large depending upon the size of the casingworked without, however, in any way altering lthe principle of operationof the device.

While I have herein shown and described my invention in what I haveconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within Ithe scope of myinvention, which is not to be limited to the details disclosed hereinbut is to be accorded the full scope of the claims so as to embrace anyand all equivalent devices.

Having described my invention, what I claim as new and desire 'to secureby Letters Patent is:

1. A shing tool for retrieving magnetizable objects from well casingscomprising a, hollow container, a magnetic piston unit slidably ttingwithin said container forming a closed chamber therein, said magneticpiston unit having a withdrawn position within the container and anextended object-engaging position at the lower end of the container, ailuid connection from Athe chamber to the surface and a shut-oli valveon the connection, a uid in said chamber adapted to be admitted theretothrough said connection, said fluid being operable upon opening of saidshut-off valve when the container is in the well to effect movement ofsaid magnetic piston unit to withdrawn position, retaining means on thecontainer for said magnetizable objects, said retainer having anobject-engaging position and means adapted automatically to move saidretainer to said object-engaging position.

2. A shing tool for retrieving magnetizable objects from well casingscomprising a hollow cylindrical container of non-magnetic material, apiston including a magnet slidably tting within said container forming aclosed chamber therein, said piston and magnet having a withdrawnposition within the container and an extended obj ect-engaging positionat the lower end of the container, a iiuid connection from the chamberto the surface and a shut-oil valve on the connection, a

o Number 8 fluid in said chamber adapted to be admitted thereto throughsaid connection, a non-magnetic cover for said magnet, a retaining meansmovably attached to the container at the open end thereof adapted toengage said objects, said retainer having a normally inoperativeposition and having an operative position adapted to engage the exteriorof an object to be retrieved, and means adapted automatically to movesaid retainer to object-engaging position.

3. A iishing tool for retrieving magnetizable objects fromwell casingscomprising a hollow cylindrical container of non-magnetic material, apiston slidably iitting within said container forming a normally closedchamber therein, said piston having a withdrawn position wherein thevolume of the chamber is diminished and an extended position wherein thevolume of said chamber is expanded, a shut-01T valve outside the casing,a fluid connection from the chamber to the shut-off valve, a fluid insaid chamber adapted to be admitted thereto under pressure through saidconnection, said iiuid being operable upon opening of said shut-offvalve to effect a movement of the piston to the withdrawn position, anelectro-magnet on said piston having a core extending vto the lower faceof the magnet and an operating device outside the casing connectedthereto, a non-magnetic cover for said electromagnet, mutually opposedretainers for said objects having pivotal connections to the containernear the open end thereof and oppositely disposed roughened surfacesthereon, a stop shoulder on the container at said open end cooperablealternately with the plunger in extended position and with the retainerswhen extended during said withdrawn position of the piston, saidretainers having lowered positions engaging the shoulder forming abottom for the container in one objectengaging position and partiallylowered positions in another object-engaging position wherein theroughened faces are in mutually opposed relationship adapted Ito graspthe exterior of an object to be retrieved, and automatically extendingmeans for said retainers adapted automatically to move said retainers tosaid object-engaging positions.

KENNETH C. HAWKINS,

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Eastwood Nov. 1, 1910 Erwin Aug. 24,1937 Brantly May 23, 1939 Murphy et al. Jan. 10, 1950 Kirby Jan. 30,1951

